1. Technical Field
The present disclosure relates to a system and method for sewage/wastewater treatment that can treat sewage/wastewater in a cost-effective way.
2. Related Art
Generally, wastewater contains nutritional substances such as nitrogen or phosphorus, sparingly soluble and toxic substances, and heavy metals. Such wastewater can be treated by a biological method or a physical/chemical method.
Typical examples of the biological wastewater treatment method include an activated sludge method employing a treatment system including a first settling tank, an aeration tank, and a final settling tank, and a sewage/wastewater treatment method employing an aerobic/anaerobic process. However, the former method requires a means for maintaining the concentration of sludge at a specific level or higher, and the latter method does not use the activated sludge process alone, but adopts a complete mixing mode in which an aerobic reaction tank and an anaerobic/oxygen-free reaction tank which are arranged in a line are operated. Thus, in the latter method, there are problems in that it is difficult to maintain microorganisms in the reaction tanks at a high concentration and in that it is difficult to maintain a complete anaerobic state during denitrification or the induction of phosphorus discharge.
Previously, the present inventors developed a sewage/wastewater treatment system and method for treating organic wastewater containing sparingly soluble and toxic substances, nutritional substances such as nitrogen or phosphorus, and heavy metals, as disclosed in Korean Patent No. 10-0287412 issued Jan. 27, 2001. The sewage/wastewater treatment system comprises a mixing unit combined with a cylindrical anaerobic/oxygen-free reaction tank. Thus, the wastewater treatment system may not be applied without modification to a conventional sewage/wastewater treatment system including a first settling tank, a reaction tank, and a final settling tank. That is, the first settling tank is required to be modified to serve as an anaerobic/oxygen-free reaction tank and the modified first settling tank is then required to be operated in combination with the existing reaction tank and final settling tank. Also, in applying the sewage/wastewater treatment method to a sewage/wastewater treatment system having a rectangular first settling tank, a new cylindrical anaerobic/oxygen-free reaction tank is required in place of the first rectangular settling tank such that the new tank can be operated in combination with the existing reaction tank and final settling tank, thereby requiring excessive equipment investment.
Accordingly, there is a need to develop a new sewage/wastewater treatment system and method.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.